Summary:
We want Mercurial to become more responsible for it's own
configuration, instead of relying on chef and other means. To do so, let's
introduce a new `hg debugdynamicconfig` that can generate dynamic configs for
a given repository based on various states, like what tier it's in or what shard
that machine is in. By default it generates to '.hg/hgrc.dynamic' for the given
repository.
Currently it just sets the hostgroup config.
Future diffs will make Mercurial consume this config, and possibly have Mercurial
call this command asynchronously when it notices the file is out-of-date.
Reviewed By: quark-zju
Differential Revision: D20828132
fbshipit-source-id: 6f5bf749f5b04e0a5989d6dc19ee788c2e47f88f
